Acceleration operated switch



Jan. 7, 1964 N. R.VVINCENT ACCELERATION OPERATED SWITCH 2 Sheets-Sheet 1 Filed Aug. 29, 1960 INV NTOR. 4/4774M44 Z Mm! BY 4 Arfoewi/ Jan. 7, 1964 N. R. VINCENT ACCELERATION OPERATED SWITCH 2 Sheets-Sheet 2 Filed Aug. 29, 1960 I N V EN TOR. 447;!44054 Z WA/cJ/V United States Patent C) 3,117,196 ACCELERAHQN @FERATED SWl'llClll Nathaniel R. Santa Monica @ahfi, assign'or to 9 Douglas Aircraft Company, lino, Santa Monica, tlahr. Filed Aug. 2%, litill, Ser. No. 52,623 11 Claims. (tjl. Elih -611.45)

This invention relates to inertia operated devices and has particular reference to an inertia operated switch which will only operate to initiate a desired operation after it has been subjected to an acceleration exceeding a critical value determined by the design and/ or setting of the switch.

Various forms of inertia operated switches are known to the prior art, but none of them, within the knowledge of the present inventor are free from certain material disadvantages which this invention has been particularly designed to overcome.

Inertia operated devices have proven of great utility on objects which are subjected to large accelerations and decelerations, such as airplanes, rockets and projectiles. For they have been used on aircraft to provide, in the event of crash or impact, an automatically operated tch to close an electrical circuit and actuate fire preventing and extinguishing appliances. In addition, such switches have been used on missiles wherein the switch is adapted to be actuated by the large acceleration force encountered during firing of the missile and is arranged to effect a desired operation when this acceleration reaches a predetermined value.

One usual form of inertia operated switch particularly adaptable for missiles use comprises: a metal ball, a permanent magnet to hold the ball in a fixed position, and a non-magnetic member surrounding the ball to guide its movement. in one such device, the non-magnetic memher is in the form of a helical track. The ball is held fixed at one end of the track. When the unit is subjected to forces developed by acceleration or shock, inertia of the ball disengages it from the magnetic field and causes it to roll along the track; wherein, at the end of the track, it completes an electrical circuit. In another form, the non-magnetic member is in the shape of an inverted cone. "Elie ball is held in the apex of the inverted cone by the action of the permanent magnet until it is acted upon by a force from acceleration or shock large enough to overcome the magnetic force. The ball then rolls outward on the cone until it completes an electrical circuit at edge of the cone.

While the above described inertia operated switches have certain distinct advantages, they also have certain disadvantages which limit their scope of operation. Because of the imminent danger to life and property that surrounds the handling of a missile, it has been found desi able to provide a means to prevent arming or" the missile until it has been projected away from surrounding objects and people. This is accomplished by using an inertia operated device associated with a normally open switch. The acceleration force of the missile operates the device which closes the switch thereby completing an electrical circuit to arm the missile.

Heretofore, commercially available inertia operated devices of the above described type and other types have been proposed broadly. While these operate, upon firing of the missile, to actuate the switch, there are inherent in their design certain disadvantages of complexity and safety. Some of these devices rely upon the magnitude of the force alone to move an inertia element to actuate the switch. This means that they can be caused to operate by shock and impact forces as well as acceleration forces. The result of this is that a careless operator or handler, dropping or jarring the missile, can arm it long before it is fired. One of the prime considerations in missile manufacture is safety. Therefore, it is imperative that a simple device be designed that cannot be operated by shock or impact but only by an acceleration force of a minimum predetermined magnitude and duration.

With this object in view, the present invention has been designed to provide a relatively simple electrical switching device adapted to be activated by a force of a mini mum predetermined magnitude and duration. Briefly, the preferred embodiment of the device comprises: a housing having two chambers separated by a wall containing an aperture; a trigger mass and a switch mass each movably mounted within one of said chambers, means associated with said masses to hold said switch mass in a fixed position under the influence of said force until said force has displaced said trigger mass 2. predetermined distance; a plurality of springs associated with said masses to exert a force upon said masses to overcome the effect of said force until it has reached a minimum predetermined magnitude; and an electrical switching means associated with the switch mass for actuation thereby.

in the accompanying drawings, in which like reference numerals are used to designate similar parts throughout, there are illustrated four slightly modified forms of what is now considered to be the preferred embodiment of the idea of this invention. The drawings, however, are for the purpose of illustration only, and are not to be taken as limiting the invention; the scope of which is to be measured entirely by the scope of the appended claims.

In the drawings:

FIG. 1 is a side elevational view of the presently pre ferred embodiment of the invention wherein a portion of the cover has been removed showing the detents, latching pin and apertures in section.

PEG. 2 is a perspective view of the presently preferred embodiment of the invention showing one side, the front containing the reset aperture and orientation marking, and the bottom showing microswitches, notches and a spring adjustment screw.

3 is a cutaway side elevational view similar to FIG. 1 showing the switching device in its actuated position.

FIG. 4 is a diagrammatic view of a first modification of the present invention showing the operating mechanism wherein the casing is represented in broken lines.

FIG. 5 is a diagrammatic view of a second modification of the present invention showing the operating mechanism wherein the casing is represented in broken lines.

Fl". 6 is a diagrammatic view of a third modification of the present invention showing the operating mechanism wherein the casing is represented in broken lines.

Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a rectangular shaped casing or housing ltl comprising a pair of side walls ll, 13, end walls 15, 7, and face surfaces 19 wherein, as Viewed in FIG. 2, said face surfaces and side walls have a greater longitudinal dimension than said end walls.

Extending through said end walls l5, 17 are a plurality of apertures. in addition to said apertures, one end wall 15 contains a pair of notches 23 and internally threaded bore 58. Extending longitudinally of said casing ill and partitioning said casing into first and second chambers 18, 29 respectively, is a partition or Wall 16. Said Wall contains a ball receiving aperture 25". End wall 15 has a web portion 22- which projects into the chamber 2%, thereby reducing the longitudinal dimension of said chamber; wheeby said chamber has a longitudinal dimension approximately three quarters of that of chamber 15%. To

enclose the chambers, a pair of plates or covers 12 are attached by conventional fastening means, such as screws 14, to the face surfaces l9.

Running longitudinally of the chambers 13, 2t) and terminating in the apertures in the end walls 15, 17 (as seen in H6. 2) are a plurality of bars or guide rods 24, 26, respectively, and within said chambers 18, Ed are re spectively a first member or trigger mass 23 and a second member or switch mass Said masses 28, 3% each have a pair of longitudinal apertures through which said bars 2-4, 26, respectively, extend to guide the movement of said masses when they are displaced by the action of the acceleration forces.

in the first chamber 18, circumscribing the bars 24- and contained between the interior surface of end wall 15 and one surface 33 of the trigger mass 28, are a plurality of motion resisting coil springs 34. Extending longitudinally of the second chamber 23 through the bore in the end wall 15 and contained between an adjustment screw 36 mated with said bore and one surface 35 of the switch 18.38 3h, is a second motion resisting coil spring 32.

in each surface of the masses 28, 39 adjacent to the partition lid is a detent or notch it), 42 respectively. In respect to the orientation of the device as shown in FIGS. 1 and 3, the notch is located in the upper portion of the trigger mass and notch 42 is located in the lower portion of the switch mass 3%. Contained within the aperture 25 in the partition 16 is a sphere or ball 44 which is freely movable and of sufficient diameter to be inserted into the notch in either the trigger or the switch mass when one of said notches is in line with the aperture.

A latch bore 54? is provided in the side of the switch mass 3r? opposite to that containing the detent 42. Contained within the latch bore Sil and bearing against the interior surface of side wall it is a spring loaded latch pin 52.. Extending through the side wall 11 in line with the longitudinal path of movement of the switch mass and near the terminus of said path is a latch detent or aperture 56.

Attached to the casing ill by conventional means (not shown) and located within the notches 23 are a plurality of microswitches 46. Said switches are of any appropriate type to operate a desired system, or systems, such as a single pole, single throw, switch used to actuate, under predetermined conditions of acceleration, the arming system of a missile. Said switches are mounted to the casing each within a notch 23 for contact by the switch mass and corresponding actuation prior to the latching of the device.

In FIG. 1, the device is depicted in the deactivated state. To actuate the device, it must be primarily accelerated in the direction as indicated by the orientation arrow 54 shown in FlG. 2. Device 16 can be attached by any suitable means to an object itla (fragmentarily shown in EEG. 3) which can be the structure of an aircraft r missile, for example. The acceleration of the object and hence device exerts a force on both the trigger mass and the switch mass, which attempts to displace the masses toward end wall I15. However, the switch mass Ell is prevented from moving by the engagement of ball 4 within detent -2 and the trigger mass 23 will not move until the acceleration force exerted by said mass upon springs is suilicient to overcome the force exerted by springs 34. When the mass 23 has moved sufficiently to bring the detent in line with the aperture 25 in the partition 16, the cam action of notch 42, under the influence of the acceleration force acting upon switch mass 3d causes the ball 44 to move out of engagement with the detent 42 and into engagement with the detent in the trigger mass. This movement of the ball frees the switch sass 3t) and it will move toward end wall 15. When, as seen in FIG. 3, the switch mass reaches its terminal point of movement, the lower surface 35 of the mass contacts the actuating arms 43 of the microswitches -2-6 ca ng the switch arm to be displaced thereby actuating the switches through engagement of the arms 4 43 with the switch buttons Subsequent to the actuation of the switches, the latch pin 52 drops into aperture 55, thereby preventing the mass from additional displacement when the acceleration force is increased or decreased.

To reset the device, the latch pin 52 must be depressed from in contact with the aperture 5'6 in the side wall 11, thereby freeing switch mass 3%, wherea'fter the force of springs 32 an 34 will cause the masses 3d, 23 respectively to return to their deactivated position within the casing as shown in PEG. 1.

By proper choice of retention springs 32, 34 the displacement of the corresponding masses can be controlled to produce activation of the switches only by an accelera tion force of a predetermined minimum magnitude and duration.

Shown in FIGS. 4, 5 and 6 are modifications of the present invention. The housing or casing of each modification is represcnted in broken lines for clarity of illustration.

in the modification shown in PEG. 4, the trigger and switch masses 128, 13d are rotatably mounted on shafts 82, 8 2- respectively. Each mass has a curved face Said faces 86 allow each mass to rotate under predetermined conditions without interference with the other mass. Projecting from one side of the trigger mass is a ringlike portion 83 having a hat cam surface W.

Extending from one edge of the curved surface of the mass 13%) into engagement with the fiat surface 9%, when the device is in the deactivated state, is a switching arm 92.

Circumscribing the shafts 32., 84 are force resisting springs 96, @4 respectively. Each spring has one of its free ends inserted into an aperture in the adjacent mass and the other free end inserted into the circumscribed shalt (not shown). Mounted to the casing within the path of rotation or the switch mass arm 92, so that it will be con tacted thereby, is a microswitch 4-6;

In the modification shown in FIG. 4 the device is in a deactivated state. The device can be attached by any suitable means to an object it'll) (fragmentarily shown in HS. 4) which can be structure of an aircraft or missile, for example. An acceleration of the object Trill) and hence the device upward, as oriented in PEG. 4, causes the trigger mass 128 to rotate about shaft 82 when the acceleration force is sufiicient to overcome the resisting force exerted on the mass by spring 96. As the mass rotates, the arm 92 will remain in contact with the cam surface 93 until the surface has rotated to a position approximately parallel with the longitudinal axis of the device. Thereafter, arm 92 is freed and t. e switch mass 136 ro tates towards the switch 46 until the arm 92 has engaged the switch arm and actuated the switch. Subsequent to this operation, the device will be latched as described above in the preferred embodiment. That is, the latch pin 52a which is similar to latch pin 52 drops into an aperture 56a that is similar to the aperture 56, in the casing of FIG. 4 to latch the device.

In a second modification shown in FIG. 5, the switch and trigger masses 225, 2.3% are located in an inline relati nship. In this modification, the motion of the masses 22$, 23% is guided by guide rods '74-, vs and resisted re spectively by springs 77, '78. The trigger mass 228 is provided with an inclined edge or kerf 6t? and the switch mass is provided with a notch and a groove 62, respectively. Engageable respectively with the inclined surface 6%, and the notch and groove s2, 64 are a pair of pins 72, 7t). Said pins are mounted on a rotatable lever The lever 66 is rotatably mounted (not shown) to the casing by a pin 63. Extending laterally from the surface of the witch mass opposite to that containing the groove 64 is a switch contact pin in the modification shown in 5 the device is shown in a deactivated state. The device can be attached by any suitable means to an object we (fragmentarily shown in PEG. 5) which can be structure of an aircraft or missile, for example. When the object lite and hence the switch is accelerated upward, as orientated in FIG. 5, the trigger mass 22% remains stationary until the force of acceleration exceeds the restraining force of spring 7'7. l hen the mass has been acted upon by suilicient force to overcome this spring force the mass moves downward, as orientated in PEG. 5, against the action of the spring and the pin 72 under the force of spring '71 moves into contact with the inclined surface 69. Additional movement of the trigger mass causes the pin to move relatively along the inclined surface, thereby resulting in a rotation of the arm 66 clockwise about the pin es. As the pin '72 reaches the upper portion of the inclined surface (it) the arm 66 has rotated sufficiently to allow the pin "I'll to move into alignment with the groove thus freeing the switch mass and allowing it to move downward until the contact pin 89 has activated the switch 46 and the device is latched as described in the preferred embodiment. That is, the latch pin 52b which is similar to latch pin 52 drops into an aperture 5651 that is similar to the aperture 56, in the casing of PM}. 5 to latch the device.

In a third modification shown in FIG. 6, the trigger and spring masses 3.28, 3%, respectively are located in an inline relationship and are guided during their movement by a single guide rod 128. The trigger mass 323 includes a notched section ltlll extending longitudinally of said mass along one side of corner thereof and having an in red portion or cam 192. The switch mass 33% includes a pair of notches @3, 99 extending along the same side as the section of said trigger mass. Each of the EMU notches 93, 99 extends from one of the transverse surfaces of said mass along said corner to a depth sufficient to provide a web M97 therebetween. Circumscribing said rod 1% are force resisting springs 122, 124;. Both springs have one end in contact with the casing. However, the free end ()5 spring 124 (which is sectionally cut away for clarity of illustration) is in contact with one surface oi the trigger mass and the free end of the other 1 ing passes through a bore in the trigger mass and is in contact with one surrace M93 of the switch mass. Adjacent to the longitudinal surfaces of said masses containing said notches 99, 1th? and engagea'ole therewith is a rotatable rocker arm llltl. Said arm has at its free end, a hooked portion and intermediate thereof a protuberance and is rotatably attached to the casing (not shown) by a pin Extending outward from the hooked portion of said arm Elli) is a manual reset oin ii Extending outward from the surface of the switch mass opposite to that containing the said notches 'l, is a switch contact pin 1% and located in line therewith, for contact thereby, is a microswitch 6. Bearagainst the surface of the rocker arm rill, opposite to that containing the hooked portion lid and protuberfilS, is the free end of a leaf spring 1316. Said spring he its other end attached to the casing (not shown).

he modification sl'iown in FIG. 6 the device is the ctivated state. The device can be attached by any suitable means to an object Edd (fragmentarily shown in FlG. 6) which can be structure of an aircraft or missile, for examgale. When the object Kidd and hence the device has been accelerated forward or upward as orientated in FIG. 6, and said acceleration force has reached a minimum magnitude suflicient to overcome the restraining force of spring 124, the trigger mass 323 moves downward. This causes the inclined cam portion 16 of notch ti -d to bear against the protuberance 2115 of the rocker arm lid, thereby rotating the arm clock- As the displacement of the trigger mass increases the arm will rotate about pin ill? thus removing the book i i from engagement with the notch This allows switch mass to move downward until the contact pin 126 has activated the switch do and the hooked portion 114- is engaged in notch reset the device the rocker arm ill) is rotated clock- 6 Wise suliiciently to remove the hook 3114 from engagement with notch 99 resulting in an upward movement of the switch mass under the force of spring 122.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described in respect to the aforesaid preferred embodiment and modifications thereof.

I claim:

1. An electrical switching device adapted to be activated only by an acceleration force of a predetermined minimum magnitude and duration, comprising: first and second movable members mutually arranged for relative movement in response to said force; means adjacent to both of said movable members for holding said se ond movable member in a solidly engaged, fixed position under the influence of said force until said force has caused said first member to be displaced a first predetermined distance at which said second member is uickly and fully released by said holding means to be free to be displaced a second predetermined distance wherein displacement thereof is effectively limited independently of the displacement of said first member to said first predetermined distance; force resisting means in contact with said movable members to exert a counteracting force upon said members, thereby resisting the movement of said members until said acceleration force has reached a minimum predetermined magnitude and duration; and an electrical contact means in juxtaposition with said second movable member and adapted to be contacted thereby when said force has reached said minimum predetermined magnitude and duration whereby an electrical circuit is actuated.

2. An inertia-type electrical switch adap d to be actuated only by an acceleration force of a mi .mum predetermined magnitude and duration, comprising: a trigger mass and a switch mass adapted for respective movements in response to said force; means adjacent to said masses adapted to hold said switch ma s in a solidly engaged, fixed position under the influence of said acceleration forces until said trigger mass has been d1 placed a first predetermined distance by said force, wucreaftsaid switch mass is quickly and fully released to be free to move a second predetermined distance wherein displace ment thereof is effectively limited independently of the displacement of said first member to said first predetermined distance; electrical contact means adapted to be contacted by said switch mass when said mass is displaced by said force, thereby actuating an electrical circuit; and spring biasing means adapted to exert a force on said masses tending to offset the effect of the acceleration force until said force has reached a minimium predetermined magnitude and duration.

3. An inertia-type electrical switch adapted to be fixedly mounted in an object subject to acceleration for actuaion only by an acceleration force or" a r .lll'lltlli'l predeter lined magnitude and duration, comp a housing secured to said object and having its longitudinal axis parallel with the longitudinal axis of the object; first and second movable members arranged in said housing for movement parallel with the longitudinal axis thereof; means adjacent to said movable members to hold said second member in a solidly engaged, fixed position under the influence of acceleration forces until said first member has been displaced a minimum first uredetemined distance at which said second member is quickly and fully released by said holding means to be free to be displaced a second predetermined distance wherein displacement thereof is eiiectively limited inde endently of e displacement of said first member to said first predetermined distance; force resisting means in contact with said movable members adapted to exert a counteracting force upon said movable members tending to offset the effect of said acceleration forces until said acceleration forces have reached a minimum predetermined magnitude and duration; and electrical contact means adapted to be contacted by said econd member to actuate an electrical circuit when said second member is displaced by said acceleration force.

4. An inertia-type electrical switch adapted to be mounted in an object subject to acceleration for actuation only by an acceleration force of a minimum predetermined magnitude and duration, comprisin a housing secured to an object and having its longitudinal axis parallel with the longitudinal axis of the object; movable members arranged in said housing for movement parallel with the longitudinal axis thereof, said movable members including a trigger mass and a switch mass; means adjacent to said masses adapted to hold said switch mass in a solidly engaged, fixed position under the influence of said acceleration force until the trigger mass has been displaced a first predetermined distance by said force at which distance said switch mass is quickly and fully released by said holding means to be free to be displaced a second predetermined distance wherein displacement thereof is effectively limited independently of the displacement of said trigger mass to said first predetermined distance; a plurality of coil springs each contained between said housing and one of said masses to exert a counteracting force upon said masses tending to offset the acceleration force until said acceleration forces have reached a minimum predetermined magnitude and duration; and electrical contact means adjacent to and in the path of movement of said switch mass whereby said contact means will open and close an electrical circuit when it is contacted by said switch mass.

5. An electrical switching means adapted to be actuated only by an acceleration force of a minimum predetermined magnitude and duration, comprising: a housing; first and second movable members arranged in said housing for movement the-rein only by said force; means adjacent to said movable members adapted to hold said second member in a fixed position under the influence of said force until said force has displaced said first member a predetermined distance; force resisting means in contact with said movable members for preventing movement of said members until said force has reached said minimum predetermined magnitude and duration; electrical contact means adapted to be contacted by said second movable member for opening and closing an electrical circuit; and means carried by said second movable means and engageable with said housing to maintain a continuous contact between said second member and said electrical contact means when said acceleration force reaches said minimum predetermined magnitude and duration.

6. An inertia-type electrical switch adapted to be mounted a translative object for actuation only by an acceleration [force of a minimum predetermined magnitude and duration, comprising: a housing having two chambers separated by a wall containing an aperture, said housing being mounted in a translative object so that its longitudinal axis is parallel with the longitudinal axis of the object; a trigger mass and a switch mass each mounted in one of said chambers and adapted for movement therein parallel with the lolwitudinal axis of said housing, and each mass having a detent in a first side adjacent to said wall; ball movably mounted in said aperture and engageable with the detent in said switch mass to hold said switching mass in a fixed position under the influence of acceleration forces until the trigger mass has been displaced sufiiciently to engage said ball in the detent in said trigger mass whereby said switching mass will be rendered free to move under the influence of acceleration forces; at least one coil spring in each of said chambers each being in contact with one of said masses and said hon "rig to exert a counteracting force upon said masses which tends to offset said acceleration forces until said force has reached a minimum predetermined magnitude and duration; and electrical Contact means adjacent to and in the path of movement of said switching mass whereby said contact means will actuate an electrical circuit when said switcning mass is freed by the engagement of said ball into the detent in said trigger mass.

7i An inertia-type electrical switch adapted to be mounted in an object susceptible to acceleration for actuation only by an acceleration of a minimum predetermined magnitude and duration, comprising: a housing having an aperture in one side thereof and two c iambers separated by a wall, said wall including an aperture therein, and said housing being mounted in said object with: its longitudinal axis parallel to the longitudinal axis of the object; a trigger mass and a switch mass each movably mounted within one of said chambers and adapted for movement therein parallel to the longitudinal axis of said housing; means adjacent to said masses to hold said switch mass in a fixed position under the influence of said 1 rce until the trigger mass has been displaced a predetermined distance by said force; a plurality of coil springs in said chambers each in contact with one of said masses and said housing to exert a counteracting force upon said masses which tends to offset the acceleration forces until the acceleration force has reached a minimum predetermined magnitude and duration; electrical contact means positioned in the path of movement of said switch mass and adapted to actuate an electrical circuit when contacted by said switching mass; and a spring loaded latching means positioned in and extending from one side of said switch mass and adapted to engage said aperture in. the housing subsequently to the activation of said switch whereby said electrical contact means is maintained in a constant activated position.

8. An inertia-type electrical switch adapted to be actuated only by an acceleration force of a minimum predetermined magnitude and duration, comprising: a trigger mass and a switch mass adapted for respective rotational movements in response to said force; said trigger mass including a ringlilte portion having a flat cam surface thereon and said switch mass including a switching arm in contact with said flat surface whereby said switch mass is held in a fixed position under the influence of said acceleration forces until said trigger mass has been rotated sufficiently to free said switching arm; spring biasing means adapted to exert a force on said masses tending to offset the effect of the acceleration force until said force has reached said minimum predetermined value; and electrical contact means adjacent to said switch mass and adapted for contact by said switching arm when said switch mass rotates under the influence of said acceleration forces.

9. An inertia-type electrical switch adapted to be fixedly mounted in an object subject to acceleration for actuation only by an acceleration force of a minimum predetermined magnitude and duration, comprising: a hollow box-like housing secured to said object and having its longitudinal axis parallel with the longitudinal axis of the object; a pair of shafts, secured in opposite walls of said housing; a trigger and a switch mass each rotatably mounted on one of said shafts for respective rotations. movements in response to said force; said masses each having a notched section adjacent to said shaft; means on said trigger and switch mass adapted to hold said switch mass in a fixed position under the influence of ZlCCfiiQfc. tion forces until said trigger mass has been rotated through a minimum predetermined arc; a pair of springs each circumscribing one of said shafts and extending transversely of one of said masses in the notched section thereof, said spring having one end secured to the inscribed shaft and the other secured to said adjacent mass wherein said springs exert a counteracting force upon said masses tending to olfset the effect of said acceleration forces until said acceleration forces have reached a minimum predetermined magnitude and duration; and electrical contact means adjacent to and in the path of rotation of said switch arm whereby said means will be contacted by said arm when said switch mass rotates under the influence of acceleration forces thereby opening or closing an electrical circuit.

10. An inertia-type electrical switch adapted to be fixedly mounted in an object subject to acceleration for actuation only by an acceleration force of a minimum predetermined magnitude and duration, comprising: a housing secured to said object and having its longitudinal axis parallel with the longitudinal axis of the object; a trigger mass and a switch mass arranged in an in-line relationship within said housing and adapted for respective movements in response to said forces, said trigger mass having a portion of a first edge notched into an inclined surface; said switch mass including a notch in the surface adjacent to said trigger mass and a groove in a first surface corresponding to the firs-t surface of said trigger mass and a contact pin extending from the surface opposite to that containing the groove; a rotatable lever mounted to said housing adjacent to the first surfaces of said trigger and switch masses, including a first and second pin respectively adapted to make contact with said trigger and switch masses; electrical contact means mounted to said housing in the path of movement of said contact pin and adapted to be contacted thereby only when said acceleration force has reached a minimum predetermined magnitude and duration; and spring biasing means adapted to exert a force upon said masses tending to offset the effect of the acceleration force until said force has reached said minimum predetermined magnitude and duration, whereafter said trigger mass moves under the influence of said force thereupon, and said lever rotates sufiiciently to bring said first pin into contact with said inclined surface, and said second pin moves into alignment with said groove, and said pin in said switch mass makes contact with said switch mass, resulting in an opening or closing of an electrical circuit.

11. An inertia-type electrical switch adapted to be fixedly mounted in an object subjected to acceleration for actuation only by an acceleration force of a minimum predetermined magnitude and duration, comprising: a housing secured to said object and having its longitudinal axis parallel with the longitudinal axis of the object; a trigger mass and switch mass arranged in an in-iine relationship within said housing and adapted for respective movement in response to said forces, said trigger mass having a notched section in one side thereof and included therein an inclined portion, said switch mass including a first and second notched section in a first side corresponding to that of the trigger mass, and an unnotched portion remaining between said notches; said switch mass also including a contact pin protruding from the side opposite to said first side; a spring loaded rotatable lever mounted to said housing adjacent to said first sides of said masses, said lever including a protuberance in contact with said inclined portion of said groove in said trigger mass and a hooked portion in contact with said first notched section in said switch mass; electrical contact means mounted to said housing in the path of movement of said contact pin and adapted to be contacted thereby only when said acceleration force has reached a minimum predetermined magnitude and duration; and spring biasing means adapted to exert a force upon said masses tending to offset the effect of the acceleration force until said force has reached said minimum predetermined magnitude and duration whereafter said masses will move in sequence to open or close an electrical circuit.

References Cited in the file of this patent UNITED STATES PATENTS 2,742,542 Bennett Apr. 17, 1956 2,354,539 Ruppel Sept. 30, 1958 2,881,277 Marks et a1 Apr. 7, 1959 2,950,908 Rainsberger et al Aug. 30, 1960 2,997,883 Wilkes Aug. 29, 1961 3,018,664 Humble Jan. 30, 1962 3,054,870 Wagoner Sept. 18, 1962 

1. AN ELECTRICAL SWITCHING DEVICE ADAPTED TO BE ACTIVATED ONLY BY AN ACCELERATION FORCE OF A PREDETERMINED MINIMUM MAGNITUDE AND DURATION, COMPRISING: FIRST AND SECOND MOVABLE MEMBERS MUTUALLY ARRANGED FOR RELATIVE MOVEMENT IN RESPONSE TO SAID FORCE; MEANS ADJACENT TO BOTH OF SAID MOVABLE MEMBERS FOR HOLDING SAID SECOND MOVABLE MEMBER IN A SOLIDLY ENGAGED, FIXED POSITION UNDER THE INFLUENCE OF SAID FORCE UNTIL SAID FORCE HAS CAUSED SAID FIRST MEMBER TO BE DISPLACED A FIRST PREDETERMINED DISTANCE AT WHICH SAID SECOND MEMBER IS QUICKLY AND FULLY RELEASED BY SAID HOLDING MEANS TO BE FREE TO BE DISPLACED A SECOND PREDETERMINED DISTANCE WHEREIN DISPLACEMENT THEREOF IS EFFECTIVELY LIMITED INDEPENDENTLY OF THE DISPLACEMENT OF SAID FIRST MEMBER TO SAID FIRST PREDETERMINED DISTANCE; FORCE RESISTING MEANS IN CONTACT WITH SAID MOVABLE MEMBERS TO EXERT A COUNTERACTING FORCE 